Capacitor apparatus of the capacity variable type

ABSTRACT

The present invention is directed to a capacitor apparatus of the capacity variable type. This capacitor apparatus is manufactured by Micro Electro-Mechanical System technology, and comprises an insulating substrate ( 2 ) in which at least two capacitor electrodes ( 3 ), ( 4 ) are formed on one surface ( 2   a ) in the state where they are insulated each other, an actuator ( 5 ) formed by insulating material and having an external shape to bridge over the respective capacitor electrodes ( 3 ), ( 4 ), the actuator ( 5 ) being such that a conductor which respectively constitutes capacitors between the conductor ( 6 ) and these capacitor electrodes ( 3 ), ( 4 ), and drive means ( 7 ) for allowing this actuator ( 5 ) to undergo an operation to come into contact with one principal surface ( 2   a ) of the insulating substrate ( 2 ) or to become away therefrom.

The subject matter of application Ser. No. 10/450,867 is incorporatedherein by reference. The present application is a continuation of U.S.application Ser. No. 10/450,867, filed Nov. 24, 2003 now U.S. Pat. No.6,885,537, which claims priority to International Application No.PCT/JP02/10485, filed Oct. 9, 2002, and Japanese Patnet ApplicationNumber JP2001-321026, filed Oct. 18, 2001. The present applicationclaims priority to these previously filed applications.

TECHNICAL FIELD

The present invention relates to a capacitor apparatus of the capacityvariable type manufactured by using Micro Electro-Mechanical System(MEMS) technology, and adapted for allowing electrostatic capacity to bevariable and for reducing parasitic inductor component by draw-out ofwiring.

BACKGROUND ART

For example, various information such as audio information or imageinformation, etc, have been handled with ease by various communicationterminal equipments with popularization of technology for realizingdigitization of data and/or compression technology thereof, andpreparation and expansion of communication system and/or service systemfor data, and availability thereof has been realized. Communicationterminal equipments are small and light in weight and is excellent inportability, and can be used for a long time, and have no necessity ofrelay device, etc. so that connections to various communication systemscan be realized. At the communication terminal equipment, at thetransmitting/receiving unit, in order to carry outmodulation/demodulation processing of analog high frequency signal,there is provided, e.g., high frequency transmitting/receiving circuitof the superheterodyne system or the direct conversion system, etc.

At the high frequency transmitting/receiving circuit, there are providedan antenna unit including an antenna and a changeover switch and servingto receive or transmit signal, a transmit/receive switching unit forcarrying out switching between transmission and reception, a frequencyconverting circuit unit, a demodulation circuit unit, a modulationcircuit unit, and a reference frequency generating circuit unit forsupplying reference frequency, etc. At the high frequencytransmitting/receiving circuit, there are provided various filtersbetween respective stages, a Voltage Controlled Oscillator (VCO) forlocal oscillation in which capacity is caused to be variable, functionalcomponents such as Surface Acoustic Wave (SAW) filter, etc., a matchingcircuit, a bias circuit, and passive components such as inductor,resistor and/or capacitor, etc. In the high frequencytransmitting/receiving circuit, for the above reason, the entiretybecomes large and power consumption also becomes large. This is greatobstacle to miniaturization and light weight, and realization of lowpower of communication terminal equipment.

With respect to the above-described voltage controlled oscillator, e.g.,as described in the Japanese Patent Application Laid Open No. 82569/1997publication, there is also employed a variable capacitor 100 in whichthe MEMS technology which forms very small electrodes or movable bodies,etc. on insulating substrate by the thin film technology or the thickfilm technology, etc. is used to thereby realize miniaturization. Asshown in FIG. 1A, the variable capacitor 100 is composed of aninsulating substrate 101, and a movable member 102 of which one end iscantilever-supported on one surface 101 a of this insulating substrate101.

At the insulating substrate 101, as shown in FIG. 1B, on one surface 101a, a rectangular drive electrode 103 and a rectangular detectionelectrode 104 are formed in the state where insulation therebetween ismaintained with each other, and a pair of draw-out electrodes 105, 106are formed in a manner positioned in correspondence with the supportingportion of the movable member 102. The movable member 102 has insulatingproperty and elasticity, and is composed of a supporting portion 107formed at one end portion, a fulcrum portion 108 formed on thissupporting portion 107 in a projected manner, and a movable portion 109integrally formed along one side portion of this fulcrum portion 108 andopposite to one surface 101 a of the insulating substrate 101 with apredetermined spacing.

As shown in FIG. 1C, the movable portion 109 has an external shapesufficient to cover the drive electrode 103 and the detection electrode104, and is adapted so that a first movable electrode 110 and a secondmovable electrode 111 are formed on the internal surface opposite to onesurface 101 a of the insulating substrate 101 respectively incorrespondence with these drive electrodes 103 and 104. The firstmovable electrode 110 and the second movable electrode 111 are conductedfrom the internal surface of the movable portion 109 to the fulcrumportion 108 and the supporting portion 107, and the supporting portion107 is respectively connected to the draw-out electrodes 105, 106 in thestate fixed on one surface 101 a of the insulating substrate 101.

In the variable capacitor 100 constituted as described above, whenexternal bias voltage is applied to the drive electrode 103 and thedraw-out electrode 105 connected to the first movable electrode 110,electrostatic force is generated between the drive electrode 103 and themovable electrode 110. In the variable capacitor 100, the movableportion 109 is attracted toward the drive electrode 103 side by thiselectrostatic force while allowing the fulcrum portion 108 to undergoelastic displacement. In the variable capacitor 100, opposite spacingbetween the detection electrode 104 and the second movable electrode 111is prescribed in the state where electrostatic force and elastic forcestored at the fulcrum portion 108 is balanced. Thus, taking-out ofelectrostatic capacity generated between these electrodes is carriedout.

In the variable capacitor 100, by adjusting external bias voltage in amanner as described above, magnitude of electrostatic force is changed.Thus, opposite spacing between the detection electrode 104 and thesecond movable electrode 111 is also changed. Since electrostaticcapacity generated between the detection electrode 104 and the secondmovable electrode 111 is proportional to inverse number of the oppositespacing, the variable capacitor 100 functions as capacitor of thevariable-capacitance type.

Meanwhile, in the variable capacitor 100, as described above, externalbias voltage is applied from the draw-out electrode 105 formed at theinsulating substrate 101 to the first movable electrode 110 of themovable member 102 side. In the variable capacitor 100, parasiticinductance which serves as line resistance component is produced betweenthe draw-out electrode 105 and the first movable electrode 110, and isconnected in series with capacitor detected by the detection electrode104 and the second movable electrode 111. Thus, LC resonator isconstituted on the whole. Accordingly, in the variable capacitor 100, asthe result of the fact that the parasitic inductance component becomesgreat, the entire resonance frequency is lowered. Thus, the frequencyregion where the variable capacitor 100 is operative as capacitorbecomes narrow.

On the other hand, in the variable capacitor 100, in order to realizelow power of equipment, it is necessary to employ a configuration suchthat the movable member 102 is driven by lower applied voltage, wherebylarge capacity change is produced between the detection electrode 104and the second movable electrode 111. In the variable capacitor 100, asdescribed above, external bias voltage sufficient to allow the fulcrumportion 108 to undergo elastic displacement is applied, whereby theopposite spacing between the detection electrode 104 and the secondmovable electrode 111 is changed. In the variable capacitor 100,consideration is also made such that, e.g., the fulcrum portion 108 iscaused to be narrow beam portion to thereby reduce elastic displacementcharacteristic to realize low voltage drive. However, in the variablecapacitor 100, by such countermeasure, there takes place the problemthat wiring between the draw-out electrode 105 at the fulcrum portion108 and the first movable electrode 110 becomes narrow so that lineresistance component becomes large.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a novel capacitorapparatus of the capacity variable type which can solve problems thatconventional variable capacitors have.

Another object of the present invention is to provide a capacitorapparatus of the capacity variable type of the micro configuration whichreduces parasitic inductor to permit operation in the high frequencyband.

A capacitor apparatus of the capacity variable type according to thepresent invention proposed in order to attain the above describedobjects comprises: an insulating substrate manufactured by MicroElectro-Mechanical System technology and adapted so that at least twocapacitors are formed on one surface in the state where insulationtherebetween is maintained with each other; an insulating actuatorhaving such an external shape to bridge over the respective capacitorelectrodes and adapted so that conductors which respectively constitutecapacitors are formed between the conductors and these capacitorelectrodes; and drive means for carrying out an operation to allow thisactuator to be in contact with the principal surface of the insulatingsubstrate or to allow this actuator to be away therefrom.

In the capacitor apparatus of the capacity variable type according tothe present invention, the actuator is caused to be close to theinsulating substrate by the drive means to thereby respectivelyconstitute capacitors between the respective capacitor electrodes andthe conductors. In this capacitor apparatus of the capacity variabletype, the actuator caused to undergo close operation with respect to theinsulating substrate by the drive means suitably adjusts oppositespacing between the actuator and the insulating substrate, wherebyrespective capacitors having a predetermined electric capacity areconstituted. In the capacitor apparatus of the capacity variable type,wiring with respect to the conductors formed at the actuator is causedto become unnecessary, whereby influence of the parasitic inductancewith respect to respective capacitors is reduced. Accordingly, thecapacitor apparatus of the capacity variable type constitutes acapacitor in which lowering of the entire resonance frequency issuppressed so that the operation in the high frequency hand can be made.

Another capacitor apparatus of the capacity variable type according tothe present invention constitutes drive means of actuator by a fixedelectrode for drive formed on one surface of an insulating substrate inthe state where insulation with respect to respective capacitorelectrodes is maintained, and a movable electrode for drive formed atthe actuator in correspondence with an electrode for drive in the statewhere insulation with respect to a conductor is maintained.

In another capacitor apparatus of the capacity variable type accordingto the present invention, a predetermined drive voltage is applied tothe drive fixed electrode and the drive movable electrode, wherebyelectrostatic force is produced between the drive fixed electrode andthe drive movable electrode, and the actuator is driven by thiselectrostatic force. In this capacitor apparatus of the capacityvariable type, since the actuator of the micro shape is driven byapplication of drive voltage after undergone positioning with highaccuracy, capacitor in which low power consumption can be realized andaccuracy is high can be constituted. In the capacitor apparatus of thecapacity variable type, since the electric signal system for capacitorand the electric signal system for actuator drive are electricallyinsulated (isolated0 from each other, mutual interference between theelectric signal system utilizing variable capacitor formed at very smallspacing and the drive signal system for actuator is reduced. Thus,improvement in the accuracy can be made.

Still more objects of the present invention and practical meritsobtained by the present invention will become more apparent from thedescription of the embodiments which will be given below with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view showing a conventional capacitor apparatusof the capacity variable type, FIG. 1B is a longitudinal cross sectionalview in the width direction thereof, and FIG. 1C is an essential partlongitudinal cross sectional view in length direction.

FIG. 2A is an essential part perspective view of a capacitor apparatusof the capacity variable type shown as a first embodiment of the presentinvention, and FIG. 2B is an essential part side view thereof.

FIG. 3 is an essential part perspective view of a capacitor apparatus ofthe capacity variable type shown as a second embodiment of the presentinvention.

FIG. 4 is an essential part exploded perspective view of the capacitorapparatus of the capacity variable type according to the presentinvention.

FIG. 5 is an essential part perspective view of a capacitor apparatus ofthe capacity variable type shown as a third embodiment according to thepresent invention.

FIG. 6A is an essential part perspective view showing a capacitorapparatus of the capacity variable type shown as a fourth embodimentaccording to the present invention in the state where actuator isdetached, and FIG. 6B is an essential part longitudinal cross sectionalview thereof.

FIG. 7 is an essential part exploded perspective view of a capacitorapparatus of the capacity variable type shown as a fifth embodiment ofthe present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A capacitor apparatus of the capacity variable type (hereinafterabbreviated as capacitor apparatus) according to the present inventionwill now be explained with reference to the attached drawings.

First, the capacitor apparatus according to the first embodiment of thepresent invention will be explained.

The capacitor apparatus 1 according to the present invention ismanufactured by the MEMS technology so as to indicate micro shape, andis composed, as shown in FIGS. 2A and 2B, of an insulating substrate 2in which a first capacitor electrode 3 and a second capacitor electrode4 are formed as film on one surface 2 a in the state where insulationtherebetweeen is maintained with each other, an actuator 5 in which aconductor 6 is formed on one surface 5 a opposite to one surface 2 a,and a drive portion 7 for driving this actuator 5. It is to be notedthat it is not limited that the capacitor apparatus 1 is manufactured bythe MEMS technology, but such capacitor apparatus 1 may be manufacturedby the general substrate formation technology, etc.

The insulating substrate 2 is comprised of, e.g., glass substrate,ceramic substrate or silicon substrate having insulating property andwhich can be formed with satisfactory surface accuracy. The insulatingsubstrate 2 is formed by organic base material having high frequencycharacteristic, e.g., polyphenol etylene, bismaleimide triazine,polyimide, liquid crystal polymer, phenol resin or polyolefine, etc. anda substrate in which the principal surface has been flattened byimplementing abrasive processing, etc. is preferably used.

At the insulating substrate 2, mask for electrode formation having apredetermined punch pattern is disposed on one surface 2 a to implementdeposition or sputtering processing of metallic material having smallelectrical resistivity, e.g., aluminum or gold, etc. to thereby form, asfilm, the first capacitor electrode 3 and the second capacitor electrode4. As shown in FIG. 2A, the first capacitor electrode 3 and the secondcapacitor electrode 4 are respectively formed so as to indicatesubstantially the same rectangular shape, wherein draw-out portions 3 a,4 a connected to external circuit are integrally formed. As describedlater, the first capacitor electrode 3 and the second capacitorelectrode 4 respectively deliver produced electrostatic capacitance toexternal circuit through the draw-out portions 3 a, 4 a. In thisexample, after the first capacitor electrode 3 and the second capacitorelectrode 4 are formed, mask for electrode formation is detached fromthe insulating substrate 2.

The actuator 5 is combined with the insulating substrate 2 in the statewhere a predetermined opposite spacing is spaced with respect to onesurface 2 a. With respect to the actuator 5, a sacrifice layer 8 (seeFIG. 2B) using, e.g., silicon dioxide or suitable organic material asmaterial is formed on one surface 2 a of the insulating substrate 2where, e.g., the first capacitor electrode 3 and the second capacitorelectrode 4 are formed as film to form such actuator 5 by using thissacrifice layer. The sacrifice layer 8 is formed as film so as to have apredetermined thickness by arranging mask for sacrifice layer formationhaving a predetermined punch pattern on one surface 2 a of theinsulating substarate 2 to implement, e.g., plasma CVD (Chemical VaporDeposition) processing or sputtering processing, etc. In this example,the mask for formation of sacrifice layer is detached from theinsulating substrate 2 after the sacrifice layer 8 is formed.

At the sacrifice layer 8, masks where punch pattern is formed arearranged within regions corresponding to the first capacitor electrode 3and the second capacitor electrode 4, and deposition processing orsputtering processing, etc. of metallic material having small electricalresistivity, e.g., aluminum or gold, etc. is implemented so that theconductor 6 is formed as film. The conductor 6 is spaced in a manneropposite to one surface 2 a of the insulating substrate 2 by thicknessof the sacrifice layer 8, and has a rectangular shape having dimensionssufficient to cover the first capacitor electrode 3 and the secondcapacitor electrode 4. In this example, the mask for formation ofconductor is detached from the insulating substrate 2 after theconductor 6 is formed.

At the conductor 6, there is formed the thin plate shaped actuator 5having external shape slightly greater than the external shape thereofand adapted for covering the entirety. At the actuator 5, mask forformation of actuator is arranged through the conductor 6 on thesacrifice layer 8 to implement, e.g., plasma CVD processing orsputtering processing, etc. to thereby form layer of silicon dioxide,silicon nitride or polycrystalline silicon, etc. having a predeterminedthickness. By detaching the mask for formation of actuator, the actuator5 is adapted so that the above-described conductor 6 is integrated onthe surface opposite to the insulating substrate 2.

At the actuator 5, there is formed, e.g., an arm portion 9 havingelasticity at one side portion. The arm portion 9 is connected to thedrive portion 7 through suitable connecting means. Although the detailis omitted, the actuator 5 is adapted so that the arm portion 9 and thedrive portion 7 constitute a supporting portion, and is supported in thestate where a predetermined spacing is held with respect to theinsulating substrate 2 through this supporting portion. It is to benoted that while the actuator 5 is adapted so that one side portion iscantilever-supported by plural arm portions 9, the actuator 5 may beboth holding supported or multi-point supported by arm portions 9suitably positioned at both side surfaces or outer circumferential sideportion.

Although the detail is omitted, the drive portion 7 is constituted by,e.g., electrostatic quantity drive mechanism, electromagnetic drivemechanism or thermo-electro drive mechanism, etc. which carries outvertical operation of the arm portion 9. The drive portion 7 lowers thearm portion 9 down to a predetermined position in accordance with acontrol signal outputted from control unit (not shown). As shown inFIGS. 2A and 2B, at the drive portion 7, the electric signal system forcapacitor where the first capacitor electrode 3 and the second capacitorelectrode 4 are connected and independent drive signal system areconstituted so that mutual interference is reduced.

At the insulating substrate 2, as described above, the first capacitorelectrode 3, the second capacitor electrode 4, and the actuator 5 inwhich the sacrifice layer 8 and the conductor 6 which cover theseelectrodes are integrated are formed in a laminated manner on onesurface 2 a. Thereafter, the sacrifice layer 8 is removed as the resultof the fact that chemical etching processing or Reactive Ion Etchingprocessing (RIE), or oxygen plasma etching processing, etc. isimplemented to form capacitor apparatus 1. The capacitor apparatus 1 isadapted so that the actuator 5 is opposite to one surface 2 a of theinsulating substrate 2 through the arm portion 9 in the state where apredetermined spacing is held. The capacitor apparatus 1 constitutes afirst capacitor and a second capacitor in which the first capacitorelectrode 3 and the second capacitor electrode 4 are connected in serieswith the conductor 6 being as a common electrode plate.

In the capacitor apparatus 1, electrostatic capacities of the firstcapacitor and the second capacitor change inversely in proportion to theopposite spacing between the first and second capacitor electrodes 3 and4 and the conductor 6. In the capacitor apparatus 1 when a controlsignal is delivered from control unit (not shown) to the drive portion7, the actuator 5 is caused to undergo movement operation toward theinsulating substrate 2 side through the arm portion 9. In the capacitorapparatus 1, opposite spacing between the actuator 5 and the insulatingsubstrate 2, i.e., the opposite spacing between the first and secondcapacitor electrodes 3 and 4 and the conductor 6 is prescribed inaccordance with control signal, and electrostatic capacities of thefirst and second capacitors change.

In the capacitor apparatus 1, as described above, the conductor 6 of themovable portion-side for changing electrostatic capacitance isindependent of the electric signal system of the capacitor, and iscaused to be of the structure in which there is no parasitic inductanceby draw-out wiring with respect to the first capacitor and the secondcapacitor. Accordingly, in the capacitor apparatus 1, the firstcapacitor and the second capacitor are caused to respectively undergoreduction of influence of parasitic inductance so that electrostaticcapacity is caused to be changeable. As a result, lowering of the entireresonance frequency is suppressed. Thus, the operation in the highfrequency band can be carried out.

Then, a second embodiment of the present invention will be explained. Asshown in FIGS. 3 and 4, the capacitor apparatus 10 of this embodiment ismanufactured by the MEMS technology so as to indicate micro shape, andthe fundamental configuration comprising an insulating substrate 11 inwhich a first capacitor electrode 12 and a second capacitor electrode 13are formed as film on one surface 11 a in the state where insulationtherebetween is maintained with each other, and an actuator 14 in whicha conductor 15 is formed on the principal surface opposite to onesurface 11 a is similar to the above-described capacitor apparatus 1.This capacitor apparatus 10 is characterized in that it is driven byelectrostatic force produced between the actuator 14 and the insulatingsubstrate 11.

The insulating substrate 11 is also comprised of glass substrate,ceramic substrate or silicon substrate. As shown in FIG. 4, at the firstregion 11 b side on one surface 11 a partitioned into a first region 11b and a second region 11 c in length direction, the first capacitorelectrode 12 and the second capacitor electrode 13 are formed in thestate arranged in parallel along one side edge in such a manner thatinsulation therebetween is maintained with each other. The firstcapacitor electrode 12 and the second capacitor electrode 13 arerespectively formed so as to indicate substantially the same rectangularshape, wherein draw-out portions 12 a, 13 a for electrostatic capacityare respectively drawn and formed at the outer circumferential edge. Thefirst and second capacitor electrodes 12 and 13 are combined with, e.g.,inductance element (not shown) and are connected thereto to therebyconstitute variable frequency filter or variable frequency transmitter.

At the insulating substrate 11, a first fixed electrode 16 for drive isformed as film on one surface 11 a. At the first drive fixed electrode16, a terminal portion 16 a for voltage supply to which drive voltagedelivered from control unit (not shown) is applied is formed at one sideportion thereof. As shown in FIG. 3, the first drive fixed electrode 16is formed in parallel state in a manner positioned at one side of thefirst region 11 b with insulation with respect to the first capacitorelectrode 12 and the second capacitor electrode 13 being maintained.

At the insulating substrate 11, a second fixed electrode 17 for drive isformed as film on one surface 11 a. The second drive fixed electrode 17is formed in the state positioned substantially at the central portionin the width direction in the vicinity of one end side of the secondregion 11 c. As described later, the second drive fixed electrode 17 isformed in correspondence with fixed position of the actuator 14. At thesecond drive fixed electrode 17, a voltage supply lead 17 a to whichdrive voltage delivered from control unit (not shown) is applied isformed at one end portion thereof. It is a matter of course that thesecond drive fixed electrode 17 is adapted so that insulation withrespect to the first drive fixed electrode 16, the first capacitorelectrode 12 and the second capacitor electrode 13 is maintained.

At the insulating substrate 11, the actuator 14 is cantilever-supportedin the state where one end portion is fixed at the second region 11 cside. The actuator 14 is formed by base material having flexibility andadapted so that at least the surface opposite to the insulatingsubstrate 11 has insulating property. As shown in FIGS. 3 and 4, theactuator 14 is composed of an integrally formed movable portion 18, anarm portion 19, and a supporting portion 20. At the actuator 14, thesupporting portion 20 is composed of a rectangular plate shaped fixedportion 21 directly laminated and formed on one surface 11 a of theinsulating substrate 11 so that it is integrated, a rising portion 22formed in a rising manner integrally at one side edge of this fixedportion. 21, and a fulcrum portion 23 bent in horizontal direction fromthe upper end edge of this rising portion 22. At the actuator 14, at theinner surface opposite to the insulating substrate 11, a drive electrodepattern 24 is formed along with the conductor 15. The drive electrodepattern 24 is composed of a movable electrode portion 25 for drive, alead portion 26, a rising lead portion 27, and a connection electrodeportion 28 for drive.

The movable portion 18 is comprised of a thin thickness rectangularplate-shaped portion having an external shape of the dimensionssufficient to cover the first region 11 b of the insulating substrate 11substantially over the entire region. At the movable portion 18, asshown in FIG. 4, the surface opposite to the insulating substrate 11 ispartitioned into two regions 18 a, 18 b in width direction. At themovable portion 18, the conductor 15 is formed as film within the firstregion 18 a corresponding to the first capacitor electrode 12 and thesecond capacitor electrode 13. At the movable portion 18, the drivemovable electrode portion 25 is formed as film within the second region18 b corresponding to the first drive fixed electrode 16.

The conductor 15 is formed so as to take rectangular shape havingexternal shape of dimensions sufficient to cover the entirety in amanner opposite to the first capacitor electrode 12 and the secondcapacitor electrode 13. The conductor 15 acts as a common electrodeplate with respect to the first capacitor electrode 12 and the secondcapacitor electrode 13 as described later to constitute the firstcapacitor and the second capacitor connected in series. The drivemovable electrode portion 25 is also formed so as to take rectangularshape of dimensions sufficient to cover the entirety in a manneropposite to the first drive fixed electrode 16. As described later,drive voltage is applied from control unit (not shown) to the drivemovable electrode portion 25 through the drive electrode pattern 24 toproduce electrostatic force between the drive movable electrode portion25 and the first drive fixed electrode 16. The conductor 15 and thedrive movable electrode portion 25 are adapted so that insulationtherebetween is maintained with each other.

At the movable portion 18, as shown in FIG. 4, the arm portion 19 isintegrally formed in a projected manner in the state positionedsubstantially at the central portion in width direction of one side edgeportion. The arm portion 19 has a length slightly shorter than oppositespacing between the first drive fixed electrode 16 and the second drivefixed electrode 17 of the insulating substrate 11 side, and is caused tobe narrow in width to have flexibility with respect to thicknessdirection. At the arm portion 19, a lead portion 26 which has been drawnout from the drive movable electrode portion 25 formed at the movableportion 18 is formed as film over the entire region in length directionat the surface opposite to the insulating substrate 11. The arm portion19 is adapted so that when the actuator 14 is driven in such a mannerthat the movable portion 18 becomes close to the insulating substrate 11side as described later, it reduces elastic force to be stored to haveability to obtain large-displacement by small operating voltage. At thearm portion 19, a fulcrum portion 23 of the supporting portion 20 isintegrally provided at the front end portion thereof so that it isconnected thereto.

The supporting portion 20 is integrally formed in the state where crosssectional shape of the above-described fixed portion 21, rising portion22 and fulcrum portion 23 is caused to be substantially crank shape. Asthe result of the fact that the bottom surface of the fixed portion 21is integrated onto one surface 11 a of the insulating substrate 11, thefixed portion 21 cantilever-supports the actuator 14. The rising portion22 holds the fixed portion 21 and the fulcrum portion 23, i.e., thesupporting portion 20 and one surface 11 a of the insulating substrate11 so that they have a predetermined opposite spacing. As the result ofthe fact that the front end portion of the arm portion 19 is integratedwith respect to substantially the central portion of one side edge inlength direction, the supporting portion 23 supports this. At thesupporting portion 20, the lead portion 26 of the drive electrodepattern 24 formed at the arm portion 19 is extended to the fulcrumportion 23. A rising lead portion 27 formed at the internal surface ofthe rising portion 22 is continued to this extended end so that it isformed as film. At the supporting portion 20, a connection electrodeportion 28 for drive continuous to the rising lead portion 27 is formedas film on the bottom surface of the fixed portion 21.

As shown in FIG. 3, the actuator 14 constituted as described above iscantilever-supported by the insulating substrate 11 in the state wherethe fixed portion 21 is fixed on one surface 11 a. The actuator 14 isheld in a manner spaced by a predetermined spacing by the rising portion22. Thus, the movable portion 18 is opposed to the first region 11 b ofthe insulating substrate 11. At the actuator 14, the conductor 15 formedat the internal surface of the movable portion 18 is opposed to thefirst capacitor electrode 12 and the second capacitor electrode 13 insuch a manner that it bridges over the respective capacitor electrodes12 and 13 to cover these electrodes to constitute first capacitor andsecond capacitor. At the actuator 14, the drive movable electrodeportion 25 is opposed in a manner to cover the first drive fixedelectrode 16. In this case, the drive movable electrode portion 25 andthe lead portion 26 of the drive electrode pattern 24 are located at theposition where they are not opposed to the first capacitor electrode 12and the second capacitor electrode 13. Thus, there results aconfiguration such that there is no influence on the first capacitor andthe second capacitor.

At the capacitor apparatus 10, drive voltage delivered from control unit(not shown) is applied to the first drive fixed electrode 16 and thesecond drive fixed electrode 17. In the capacitor apparatus 10, d.c.drive voltage delivered to the second drive fixed electrode 17 isapplied to the drive movable electrode portion 25 formed at the movableportion 18 through the drive electrode pattern 24 drawn out and formedat the surface opposite to the insulating substrate 11 with the driveconnection electrode portion 28 of the supporting portion 20 side beingas an input unit with respect to the actuator 14.

In the capacitor apparatus 10, electrostatic force is generated betweenthe first drive fixed electrode 16 and the drive movable electrodeportion 25 to attract the movable portion 18 of the actuator 14 towardthe insulating substrate 11 side. Thus, at the actuator 14, the armportion 19 is caused to undergo elastic displacement so that the movableportion 18 experiences an operation close to the insulating substrate111 side. At the actuator 14, elastic force is gradually stored at thearm portion 19 in a manner accompanying with the operation of the thismovable portion 18. At the actuator 14, the operation of the movableportion 18 is stopped at the position where electrostatic force betweenthe first drive fixed electrode 16 and the drive movable electrodeportion 25 and elastic force stored at the arm portion 19 is balanced,and this state is held.

At the capacitor apparatus 10, opposite spacing between the conductor 15formed at the movable portion 18 and the first and second capacitorelectrodes 12, 13 formed at the insulating substrate 11 is prescribed ina manner accompanying with the operation of the above-described actuator14. Thus, electrostatic capacities of the first and second capacitorsconstituted by these components change.

In the capacitor apparatus 10, since electrostatic force generatedbetween the first drive fixed electrode 16 and the drive movableelectrode portion 25 changes by magnitude of applied drive voltage, itis possible to control operating quantity of the actuator 14.Accordingly, the capacitor apparatus 10 controls drive voltage, therebymaking it possible to take out arbitrary electrostatic capacity.

The capacitor apparatus 10 shown in FIGS. 3 and 4 has the structure inwhich the electric signal system for capacitor by first capacitorelectrode 12, second capacitor electrode 13, and conductor 15 and thedrive electric system for the actuator 14 by the first drive fixedelectrode 16 and the drive movable electrode portion 25 are independenteach other. Accordingly, the capacitor apparatus 10 has the structuredraw-out wiring of the drive electric system is not included in theelectric signal system for capacitor. Thus, parasitic inductance bydraw-out wiring with respect to the first capacitor and the secondcapacitor is reduced. Thus, in the capacitor apparatus 10, influence ofparasitic inductance is reduced in the first capacitor and the secondcapacitor. As a result, electrostatic capacity is caused to be variableand lowering of the entire resonance frequency is suppressed. Theoperation in the high frequency band can be carried out.

In the capacitor apparatus 10 of the second embodiment, the fundamentalmethod of forming actuator 14, conductor 15 and respective electrodes onone surface 11 a of insulating substrate 11 by making use of the thinfilm formation technology or the thick film formation technology iscaused to be similar to that of the above-described capacitor apparatus1.

The capacitor apparatus 10 of the second embodiment is characterized inpractical formation method for actuator 14 and drive electrode pattern24. Namely, at the manufacturing process of the capacitor apparatus 10,first capacitor electrode 12, second capacitor electrode 13, first drivefixed electrode 16 and second drive fixed electrode 17 are formed asfilm on one surface 11 a of insulating substrate 11, and sacrifice layeris then formed. In this case, this sacrifice layer is formed as filmwith a predetermined thickness on one surface 11 a of insulatingsubstrate 11 in the state where second drive fixed electrode 17 isexposed. The sacrifice layer is formed on insulating substrate 11 in thestate where the region corresponding to fixed portion 21 of actuator 14is exposed.

In the manufacturing process for the capacitor apparatus 10, electrodeformation masks where punch patterns are formed are respectivelyarranged within regions corresponding to first capacitor electrode 12,second capacitor electrode 13, first drive fixed electrode 16 and seconddrive fixed electrode 17 on the principal surface of the sacrificelayer. In the manufacturing process for capacitor apparatus 10,deposition processing or sputtering processing, etc. of metallicmaterial having small electrical resistivity, e.g., aluminum or gold,etc. is implemented, whereby conductor 15 opposite to first capacitorelectrode 12 and second capacitor electrode 13, and drive electrodepattern 24 opposite to first drive fixed electrode 16 are formed as filmon one surface of the sacrifice layer. In the capacitor apparatus 10,since second drive fixed electrode 17 is exposed from the sacrificelayer as described above, the drive connection electrode portion 28 ofthe drive electrode pattern 24 is integrally formed with respect to thissecond drive fixed electrode 17.

In the manufacturing process for the capacitor apparatus 10, in thestate where electrode formation mask is detached, sacrifice layer iscovered on insulating substrate 11 and actuator formation mask in whichexternal shape of actuator 14 is caused to be punch pattern is disposedto implement, e.g., sputtering processing or plasma CVD processing, etcto thereby form, as film, layer consisting of silicon dioxide, siliconnitride or polycrystalline silicon having a predetermined thickness. Inthe capacitor apparatus 10, since corresponding region of the fixedportion 21 is caused to be non-formation region of the sacrifice layeras described above, this fixed portion 21 is integrated on one surface11 a of insulating substrate 11 so that actuator 14 is formed as film onthe sacrifice layer.

In the manufacturing process for the capacitor apparatus 10, theactuator formation mask is detached thereafter to implement chemicaletching processing, etc. to thereby remove the sacrifice layer to formthe capacitor apparatus 10. In the capacitor apparatus 10, as describedabove, the fixed portion 21 is fixed on one surface 11 a and theactuator 14 to which the movable portion 18 is opposite to one surface11 a with a predetermined opposite spacing through the arm portion 19 isformed in the state where it is cantilever-supported by the insulatingsubstrate 11. It is to be noted that, in the capacitor apparatus 10,actuator formation mask including a punch pattern of suitable shape isused, whereby there is formed, e.g., actuator 14 of both holdingsupporting or multi-point supporting in which plural arm portions 19 orsupporting portions 20 are integrally formed is formed at suitable outercircumferential edge of the movable portion 18.

Then, a third embodiment according to the present invention will beexplained. As shown in FIG. 5, capacitor apparatus 30 of this embodimentis also manufactured so as to take micro shape by the MEMS technology,and the fundamental configuration comprising insulating substrate 11 inwhich first capacitor electrode 12 and second capacitor electrode 13 areformed as film on one surface 11 a in the state where insulationtherebetween is maintained with each other is similar to theabove-described capacitor apparatus 10. Accordingly, with respect to thecapacitor apparatus 30, common reference numerals are respectivelyattached to respective portions of the insulating substrate 11 side, andthe detailed explanation will be omitted.

The capacitor apparatus 30 of the third embodiment is adapted so thatthe configuration in which an actuator 31 is cantilever-supported in thestate where a predetermined spacing is held with respect to one surface11 a of the insulating substrate 11 is similar to the capacitorapparatus 10, but has the configuration that a conductor 32 is formed asfilm on the other surface of the opposite side with respect to onesurface 11 a opposite to the insulating substrate 11 of this actuator 31and a drive electrode pattern 33 is drawn and formed. Namely, theactuator 31 is similar to the above-described actuator 14 in thefundamental configuration composed of an integrally formed movableportion 34, an arm portion 35 integrally projected substantially at thecentral portion of one side edge of this movable portion 34, and asupporting portion 36 integrally formed at the other end of this armportion 35.

The movable portion 34 is comprised of a thin thickness rectangularshaped portion having an external shape of dimensions sufficient tocover first region 11 b of insulating substrate 11 substantially overthe entire region, and is adapted so that one surface of the actuator 31is partitioned into two regions 34 a, 34 b in width direction. At themovable portion 34, the conductor 32 is formed as film within the firstregion 34 a corresponding to the first and second capacitor electrodes12 and 13 of the insulating substrate 11 side. The conductor 32 takesrectangular shape having external shape of dimensions sufficient tocover the entirety in a manner opposite to the first capacitor electrode12 and the second capacitor electrode 13. The conductor 32 acts(functions) as a common electrode plate with respect to the firstcapacitor electrode 12 and the second capacitor electrode 13 through themovable portion 34 to constitute the first capacitor and the secondcapacitor connected in series.

At the movable portion 34, a movable electrode portion 37 for drive ofthe drive electrode pattern 33 is formed as film in the state whereinsulation with respect to the conductor 32 is maintained with eachother within the second region 34 b corresponding to the first drivefixed electrode 16. The drive electrode pattern 33 is composed of thedrive movable electrode portion 37, and a lead portion 38 drawn out andformed at the arm portion 35 and the supporting portion 36. The drivemovable electrode portion 37 takes a rectangular shape of dimensionssufficient to cover the entirety in a manner opposite to the first drivefixed electrode 16. A drive voltage is applied from control unit (notshown) to the drive movable electrode portion 37 through the driveelectrode pattern 33. Thus, the drive movable electrode portion 37generates electrostatic force.

The arm portion 35 is caused to be narrow in width to thereby haveflexibility with respect to thickness direction to reduce elastic forcestored when the actuator 31 is driven to have ability to obtain largedisplacement by small operating voltage. At the arm portion 35, afulcrum portion 39 of the supporting portion 36 is integrally connectedand provided at the front end portion thereof. Similarly to theabove-described actuator 14, the supporting portion 36 is composed of arectangular plate shaped fixed portion 39 directly laminated and formedon one surface 11 a of the insulating substrate 11 so that it isintegrated, a rising portion 40 integrally formed in a rising manneralong one side edge of this fixed portion 39, and a fulcrum portion 41bent in horizontal direction from the upper end edge of this risingportion 40, and is integrally formed so that cross sectional shape takessubstantially crank shape to hold the movable portion 34 in the state ofa predetermined opposite spacing is held with respect to the insulatingsubstrate 11.

At the arm portion 35, the lead portion 38 which has been drawn out fromthe drive movable electrode portion 37 formed at the movable portion 34is formed as film over the entire-region in length direction. At thesupporting portion 36, the lead portion 38 is formed as film in a mannercontinuous to the fixed portion 39, the rising portion 40 and thefulcrum portion 41. The lead portion 38 is integrated with the seconddrive fixed electrode 17 of the insulating substrate 11 side at thelower end portion of the outside surface of the fixed portion 39.

At the capacitor apparatus 30, electrostatic force is generated betweenthe first drive fixed electrode 16 and the drive movable electrodeportion 37 to attract the movable portion 34 of the actuator 31 towardthe insulating substrate 11 side. Thus, at the capacitor apparatus 30,the arm portion 35 of the actuator 31 is caused to undergo elasticdisplacement so that the movable portion 34 experiences an operationclose to the insulating substrate 11 side. At the capacitor apparatus30, the actuator 31 is held in the stable state at the position whereelectrostatic force between the first drive fixed electrode 16 and thedrive movable electrode portion 37 and elastic force stored at the armportion 35 is balanced.

At the capacitor apparatus 30, opposite spacing between the conductor 32formed at the movable portion 34 and the first and second electrodes 12and 13 formed at the insulating substrate 11 is prescribed in a manneraccompanying with the operation of the above-described actuator 31.Thus, electrostatic capacities of the first and second capacitorsconstituted by these components change.

Also in the capacitor apparatus 30 of the third embodiment, sinceelectrostatic force generated between the first drive fixed electrode 16and the drive movable electrode portion 37 changes by magnitude ofapplied drive voltage, it is possible to control operating quantity ofthe actuator 31. Accordingly, the capacitor apparatus 30 controls drivevoltage, thereby making it possible to take out arbitrary electrostaticcapacity.

The capacitor apparatus 30 shown in FIG. 5 also has the structure thatthe electric signal system for capacitor by the first capacitorelectrode 12, the second capacitor electrode 13 and the conductor 32 andthe drive electric system for the actuator 31 by the first drive fixedelectrode 16 and the drive movable electrode portion 37 are independenteach other. Accordingly, the capacitor apparatus 30 has the structure inwhich draw-out wiring of the drive electric system does not exist in theelectric signal system for capacitor. As a result, parasitic inductanceby draw-out wiring with respect to the first capacitor and the secondcapacitor is reduced. Thus, at the capacitor apparatus 30, influence ofparasitic inductance is reduced in the first and second capacitors. As aresult, electrostatic capacity is caused to be variable and lowering ofthe entire resonance frequency is suppressed. Thus, the operation in thehigh frequency band can be carried out.

At the capacitor apparatus 30, the first and second capacitor electrodes12 and 13 and the conductor 32 which respectively constitute the firstand second capacitors are placed in the state electrically isolated bythe movable portion 34 of the actuator 31. Accordingly, even in the casewhere impact, etc is applied to the capacitor apparatus 30, there is nopossibility that the first capacitor electrode or the second capacitorelectrode 13 and the conductor 32 are directly in contact with eachother. Thus, occurrence of excessive current can be securely prevented.In addition, at the capacitor apparatus 30, the actuator 31 is drivenuntil the internal surface of the movable portion 34 comes into contactwith one surface 11 a of the insulating substrate 11, thereby making itpossible to prescribe the maximum values of electrostatic capacities ofthe first and second capacitors by thickness of the movable portion 34.

At the capacitor apparatus 30, the fundamental method of formingactuator 31, conductor 32 and respective electrodes on one surface 11 aof the insulating substrate 11 is similar to that of the above-describedcapacitor apparatus 10, but the practical formation method for actuator31, conductor 32 and drive electrode pattern 33 is different therefrom.Namely, in the manufacturing process for the capacitor apparatus 30,first capacitor electrode 12, second capacitor electrode 13, first drivefixed electrode 16 and second drive fixed electrode 17 are formed asfilm on one surface 11 a of the insulating substrate 11, and sacrificelayer is then formed. In this case, this sacrifice layer is formed asfilm with a predetermined thickness on one surface 11 a of theinsulating substrate 11 in the state where the second drive fixedelectrode 17 is exposed. In addition, the sacrifice layer is formed onthe insulating substrate 11 in the state where region corresponding tothe fixed portion 39 of the actuator 31 is exposed.

In the manufacturing process for the capacitor apparatus 30 of the thirdembodiment, sacrifice layer is covered on the insulating substrate 11,and actuator formation mask where external shape of the actuator 31 iscaused to be punch pattern is arranged to implement, e.g., sputteringprocessing or plasma CVD processing, etc. to thereby form, as film,layer consisting of silicon dioxide, silicon nitride or polycrystallinesilicon, etc. having a predetermined thickness. In the manufacturingprocess for the capacitor apparatus 30, since corresponding region ofthe fixed portion 39 is caused to be non-formation region of thesacrifice layer as described above, this fixed portion 39 is integratedon one surface 11 a of the insulating substrate 11 so that silicondioxide layer corresponding to the actuator 31 is formed as film on thesacrifice layer.

In the manufacturing process for the capacitor apparatus 30, in thestate where the actuator formation mask is detached, electrode formationmasks where punch patterns are formed are respectively arranged withinregions corresponding to conductor 32 and drive electrode pattern 33 onone surface of the actuator 31. In the manufacturing process for thecapacitor apparatus 30, deposition processing or sputtering processing,etc. of metallic material having small electrical resistivity, e.g.,aluminum or gold, etc. is implemented, whereby conductor 32 opposite tothe first capacitor electrode 12 and the second capacitor electrode 13and drive electrode pattern 33 opposite to the first drive fixedelectrode 16 are formed as film on one surface of the actuator 31.

In the manufacturing process for the capacitor apparatus 30, electrodeformation mask is detached thereafter to implement chemical etchingprocessing, etc. to thereby remove sacrifice layer to form capacitorapparatus 30. At the capacitor apparatus 30, as described above,actuator 31 in which fixed portion 39 is fixed on one surface 11 a andmovable portion 34 is opposite to one surface 11 a with a predeterminedopposite spacing through arm portion 35 is formed in the state where itis cantilever-supported by the insulating substrate 11.

At the capacitor apparatus 30, drive electrode pattern 33 includingconductor 35 and drive movable electrode portion 37 is drawn out andformed on one surface. At the capacitor apparatus 30, the driveelectrode pattern 33 is drawn out from drive movable electrode portion37 formed at the movable portion 34 of the actuator 31, and is drawnaround at the outside surface of the arm portion 35 and the supportingportion 36. Thus, the drive electrode pattern 33 is integrated with thesecond drive fixed electrode 17 through the fulcrum portion 41. It is tobe noted that at the capacitor apparatus 30, actuator formation maskhaving a suitable punch pattern may be used to thereby form actuator 31of both holding support or multi-point support in which, e.g., pluralarm portions 35 or supporting portions 36 are integrally formed at theouter circumferential edge of the movable portion 34.

Then, a fourth embodiment of the present invention will be explained. Asshown in FIG. 6A, capacitor apparatus 50 according to the fourthembodiment is also manufactured by the MEMS technology so as to indicatemicro shape, and is similar to the above-described capacitor apparatus10 with respect to the fundamental configuration comprising insulatingsubstrate 11 in which first capacitor electrode 12 and second capacitorelectrode 13 are formed as film on one surface 11 a in the state whereinsulation therebetween is maintained with each other. As shown in FIG.6B, the capacitor apparatus 50 is characterized in the configuration inwhich an insulating body 51 which covers first capacitor electrode 12,second capacitor electrode 13 and first drive fixed electrode 16 formedon one surface 11 a of the insulating substrate 11 is formed. Sinceother configuration comprises the configuration similar to the capacitorapparatus 10 of the previously described first embodiment, the samereference numerals are respectively attached to common portions and thedetailed explanation will be omitted.

At the capacitor apparatus 50, as shown in FIG. 6A, first capacitorelectrode 12 and second capacitor electrode are formed as film on onesurface 11 a of the insulating substrate 11 in the state whereinsulation therebetween is maintained with each other, and first drivefixed electrode 16 and second drive fixed electrode 17 are formed asfilm in the state where insulation with respect to respective electrodesis maintained. At the capacitor apparatus 50, although not shown,actuator 11 is cantilever-supported with respect to the insulatingsubstrate 11. At the actuator 14, at the internal surface opposite toone surface 11 a of the insulating substrate 11, conductor 15 is formedas film in correspondence with the first capacitor electrode 12 and thesecond capacitor electrode 13, and drive electrode pattern 24 includingdrive movable electrode portion 25 corresponding to the first drivefixed electrode 16 is formed as film.

In the manufacturing process for the capacitor apparatus 50 of thefourth embodiment, similarly to the manufacturing process for theabove-described capacitor apparatus 10, electrode formation mask wherethe portions corresponding to first capacitor electrode 12, secondcapacitor electrode 13, first drive fixed electrode 16 and second drivefixed electrode 17 are caused to be punch pattern is arranged on onesurface 11 a of the insulating substrate 11. In the manufacturingprocess for the capacitor apparatus 50, deposition processing orsputtering processing, etc. of metallic material having small electricalresistivity, e.g., aluminum or gold, etc. is implemented in this stateso that first capacitor electrode 12, second capacitor electrode 13,first drive fixed electrode 16 and second drive fixed electrode 17 areformed as film on one surface 11 a of the insulating substrate 11.

In the manufacturing process for the capacitor apparatus 50, in thestate where electrode formation mask is detached, the insulating body 51which covers first capacitor electrode 12, second capacitor electrode 13and first drive fixed electrode 16 is formed. The insulating body 51 isformed by, e.g., a method of bonding resin film onto one surface 11 a ofthe insulating substrate 11, or arranging mask where a predeterminedpunch pattern is formed to coat insulating paste, etc. At the insulatingbody 51, there is no necessity of completely covering the entirety ofthe first capacitor electrode 12, the second capacitor electrode 13 andthe first drive fixed electrode 16. The insulating body 51 may havedimensions intervening between at least these respective electrodes andthe conductor portion 15 or the drive movable electrode portion 25formed at the actuator 14 side. It is to be noted that while thecapacitor apparatus 50 is adapted so that insulating body 50 is formedat the insulating substrate 11 side as described above, it is a matterof course that insulating body 51 may be formed at the actuator 14 side.

In the manufacturing process for the capacitor apparatus 50, afterformation process for the insulating body 51 is implemented, capacitorapparatus 50 is formed via the above-described formation process for thesacrifice layer, formation process for respective electrodes of theactuator 14 side, formation process for actuator 14, and removal processfor sacrifice layer, etc. It is to be noted that in the case wherechemical etching processing is implemented to remove sacrifice layer,such a material which is not etched at the same time is selected so thatthe insulating body 51 is formed.

At the capacitor apparatus 50, first capacitor electrode 12, secondcapacitor electrode 13, conductor 15 and drive movable electrode portion25 which constitute the first capacitor and the second capacitor areplaced in the state electrically isolated by the insulating body 51.Accordingly, even in the case where impact, etc. is applied to thecapacitor apparatus 50, there is no possibility that the first capacitorelectrode 12 or the second capacitor electrode 13 and conductor 15 ordrive movable electrode portion 25 are directly in contact with eachother. Thus, occurrence of excessive current is securely prevented. Inaddition, at the capacitor apparatus 50, the actuator 14 is driven untilthe internal surface of the movable portion 18 comes into contact withone surface 11 a of the insulating substrate 11 to thereby have abilityto prescribe the maximum values of electrostatic capacities of the firstand second capacitors by thickness of the insulating body 51.

Then, a fifth embodiment of the present invention will be explained. Asshown in FIG. 7, capacitor apparatus 60 according to the fifthembodiment is manufactured by the MEMS technology so as to indicatemicro shape, and is similar to the above-described capacitor apparatus10 with respect to the fundamental configuration in which an insulatingsubstrate 61 is provided and an actuator 62 is assembled with respect toone surface 61 a of this insulating substrate 61 so that it comes intocontact therewith or is away therefrom. The capacitor apparatus 60 isadapted so that a first drive fixed electrode 63 for drive and a secondfixed electrode 64 for drive are formed as film on one surface 61 a ofthe insulating substrate 61 in the state where insulation therebetweenis maintained with each other. In this case, the capacitor apparatus 60is characterized in the configuration in which capacitor electrodeswhere insulation with respect to these respective electrodes ismaintained are composed of first to third capacitor electrodes 65 to 67.

Namely, at the capacitor apparatus 60, laterally elongated rectangularinsulating substrate 61 comprised of glass substrate, ceramic substrateor silicon substrate is partitioned into a first region 61 b and asecond region 61 c in length direction. The insulating substrate 61 isadapted so that first capacitor electrode 65 to third capacitorelectrode 67 are formed in a manner arranged in parallel in the statewhere insulation therebetween is maintained with each other along oneside edge at the first region 61 side on one surface 61 a. The firstcapacitor electrode 65 to the third capacitor electrode 67 respectivelytake substantially the same rectangular shape, and are adapted so thatdraw-out portions 65 a to 67 a for electrostatic capacity arerespectively drawn out and formed at the outer circumferential edge, andare combined with, e.g., inductance elements (not shown) and areconnected thereto to constitute variable frequency filter or variablefrequency transmitter.

At the insulating substrate 61, the first drive fixed electrode 63 isformed as film in the state positioned at one side of first region 61 bof one surface 61 a. The first drive fixed electrode 63 includes, at oneside portion, a voltage supply lead 63 a to which drive voltagedelivered from control unit (not shown) is applied. At the insulatingsubstrate 61, the second drive fixed electrode 64 is formed as film inthe state positioned substantially at the central portion in widthdirection in the vicinity of one end side of second region 61 c of onesurface 61 a. The second drive fixed electrode 64 is formed incorrespondence with fixed position of the actuator 62. At the seconddrive fixed electrode 64, there is formed, at one end portion, a voltagesupply lead 64 a to which drive voltage delivered from control unit (notshown) is applied.

At the insulating substrate 61, the actuator 62 is cantilever-supportedin the state where one end portion is fixed at the second region 61 cside. The actuator 62 is formed by base material having flexibility andsuch that at least the surface opposite to the insulating substrate 61has insulating property. The actuator 62 is composed of a movableportion 68, an arm portion 69 and a supporting portion 70. At theactuator 62, the supporting portion 70 is composed of a rectangularplate-shaped fixed portion 71 directly laminated and formed on onesurface 61 a of the insulating substrate 61 so that it is integrated, arising portion 72 formed in a rising manner integrally at one side edgeof this fixed portion 71, and a fulcrum portion 73 bent in horizontaldirection from the upper end edge of this rising portion 72. At theactuator 62, a conductor 74 and a drive electrode pattern 75 are formedas film at the internal surface opposite to the insulating substrate 61.The drive electrode pattern 75 is composed of a movable electrodeportion 76 for drive, a lead portion 77, a rising lead portion 78, and aconnection electrode portion 79 for drive.

The movable portion 68 is comprised of thin thickness rectangularplate-shaped portion having external shape of dimensions sufficient tocover first region 61 b of the insulating substrate 61 substantiallyover the entire region. The movable portion 68 is adapted so that thesurface opposite to the insulating substrate 61 is partitioned into tworegions 68 a, 68 b in width direction. At the movable portion 68, theconductor 74 is formed as film within the first region 68 acorresponding to the first capacitor electrode 65 to the third capacitorelectrode 67. At the movable portion 68, the drive movable electrodeportion 76 of the drive electrode pattern 75 is formed as film withinthe second region 68 b corresponding to the first drive fixed electrode63.

The conductor 74 is formed so as to take rectangular shape havingexternal shape of dimensions sufficient to cover the entirety in amanner opposite to the first capacitor electrode 65 to the thirdcapacitor electrode 67. The conductor 74 acts (functions) as a commonelectrode plate with respect to the first capacitor electrode 65 to thethird capacitor electrode 67 as described later to constitute first tothird capacitors which are connected in series. The drive movableelectrode portion 76 is also formed so as to take rectangular shape ofdimensions sufficient to cover the entirety in a manner opposite to thefirst drive fixed electrode 63. A drive voltage is applied from controlunit (not shown) to the drive movable electrode portion 76 through thedrive electrode pattern 75 to generate electrostatic force between thedrive movable electrode portion 76 and the first drive fixed electrode63. The conductor 74 and the drive movable electrode portion 76 areelectrically insulated.

The arm portion 69 is caused to be narrow in width to thereby haveflexibility with respect to thickness direction. At the arm portion 69,at the surface opposite to the insulating substrate 61, the lead portion77 which has been drawn out from the drive movable electrode portion 76formed at the movable portion 68 is formed as film extending over theentire region in length direction. The arm portion 69 is adapted so thatwhen the actuator 62 is driven so that the movable portion 68 becomesclose to the insulating substrate 61 side, it reduces elastic force tobe stored to have ability to obtain large displacement by smalloperating voltage.

The supporting portion 70 is integrally connected to the front endportion of the arm portion 69, and is integrally formed so that thefixed portion 71 the rising portion 72 and the fulcrum portion 73 takesubstantially crank shape in cross sectional shape. As the result of thefact that the bottom surface of the fixed portion 71 is integrated onone surface 61 a of the insulating substrate 61, the supporting portion70 cantilever-supports the actuator 62. The supporting portion 70 holdsthe fixed portion 71 and the fulcrum portion 73, i.e., the movableportion 68 by the rising portion 22 at a predetermined opposite spacingwith respect to one surface 61 a of the insulating substrate 61. At thesupporting portion 70, the lead portion 77 of the drive electrodepattern 75 formed at the arm portion 69 is extended to the fulcrumportion 73, and the rising lead portion 78 formed at the internalsurface of the rising portion 72 is continuous to this extended end, andis formed as film. At the supporting portion 70, a connection electrodeportion 79 for drive continuous to the rising lead portion 78 is formedas film on the bottom surface of the fixed portion 71.

The actuator 62 is cantilever-supported by the insulating substrate 61in the state where the fixed portion 71 is integrated on one surface 61.The actuator 62 is adapted so that opposite spacing is held by therising portion 72 so that the movable portion 68 is opposed to the firstregion 61 b of the insulating substrate 61. At the actuator 62, theconductor 74 formed at the internal surface of the movable portion 68 isopposed in a manner to bridge over the first capacitor electrode 65 tothe third capacitor electrode 67 to cover these electrodes thus toconstitute the first capacitor to the third capacitor. In addition, atthe actuator 62, the drive movable electrode portion 76 is opposed in amanner to cover the first drive fixed electrode 63, but the driveelectrode pattern 75 is located at the position which is not opposite tothe first capacitor electrode 65 to the third capacitor electrode 67.Thus, there is employed a configuration such that there is no influenceon the first capacitor to the third capacitor.

At the capacitor apparatus 60, a drive voltage delivered from controlunit (not shown) is applied to the first drive fixed electrode 65 andthe second drive fixed electrode 66. At the capacitor apparatus 60, d.c.drive voltage delivered to the second drive fixed electrode 66 isapplied to the drive movable electrode portion 76 formed at the movableportion 68 through the drive electrode pattern 75 drawn around andformed at the surface opposite to the insulating substrate 61 with thedrive connection electrode portion 79 of the supporting portion 70 sidebeing as input unit with respect to the actuator 62.

In the capacitor apparatus 60 shown in FIG. 7, electrostatic force isgenerated between the first drive fixed electrode 65 and the drivemovable electrode portion 66 to attract the movable portion 68 of theactuator 62 toward the insulating substrate 61 side. Thus, at theactuator 62, the arm portion 69 is caused to undergo elasticdisplacement so that the movable portion 68 experiences an operation tobecome close to the insulating substrate 61 side. At the actuator 62,elastic force is gradually stored at the arm portion 69 in a manneraccompanying with the operation of this movable portion 68. At theactuator 62, the operation of the movable portion 68 is stopped at theposition where electrostatic force between the first drive fixedelectrode 64 and the drive movable electrode portion 76 and elasticforce stored at the arm portion 69 and the rising portion 72 arebalanced, and this state is held.

At the capacitor apparatus 60, opposite spacing between the conductor 74formed at the movable portion 68 and the first to third capacitorelectrodes 65 to 67 formed at the insulating substrate 61 is prescribedin a manner accompanying with the operation of the above-describedactuator 62. Thus, electrostatic capacities of the first to thirdcapacitors constituted by these electrodes change.

At the capacitor apparatus 60, since electrostatic force generatedbetween the first drive fixed electrode 63 and the drive movableelectrode portion 76 changes by magnitude of applied drive voltage, itis possible to control the operating quantity of the actuator 62.Accordingly, the capacitor apparatus 60 controls drive voltage tothereby have ability to take out an arbitrary electrostatic capacity.

At the capacitor apparatus 60, similarly to the above-describedrespective capacitor apparatuses, there is employed the structure thatthe electric signal system for capacitor by the first to third capacitorelectrodes 65 to 67 and the conductor 74 and the drive electric systemfor the actuator 62 by the first drive fixed electrode 63 and the driveelectrode pattern 75 including the drive movable electrode portion 76are independent each other. Accordingly, the capacitor apparatus 60 hasthe structure that draw-out wiring of the drive electric system does notexist in the electric signal system for capacitor. Thus, parasiticinductance by draw-out wiring with respect to the first to thirdcapacitors is reduced. Thus, at the capacitor apparatus 60, influence ofparasitic inductance is reduced in the first to third capacitors. As aresult, electrostatic capacity is caused to be variable and lowering ofthe entire resonance frequency is suppressed. Thus, the operation in thehigh frequency band can be carried out.

At the capacitor apparatus 60, as described above, first to thirdcapacitors are constituted by the first to third capacitor electrodes 65to 67 and the conductor 74. At the capacitor apparatus 60, e.g., thesecond capacitor electrode 66 is caused to be common electrode, and thefirst and third capacitor electrodes 65 and 67 are caused to be othercapacitor electrode, thereby also making it possible to constitute dobleoperating capacitor which carries out interlocking operation.

Moreover, at the capacitor apparatus 60, as described above, the firstto third capacitor electrodes 65 to 67 are respectively formed so as totake the same shape. At the capacitor apparatus 60, e.g., the first tothird capacitor electrodes 65 to 67 are formed so that their areas aredifferent from each other, thereby also making it possible to constitutedouble operating variable capacitor in which electrostatic capacity isvariable and its variable range is different.

Further, while first to third capacitor electrodes 65 to 67 are formedas film on one surface 61 a of the insulating substrate 61 as describedabove in the capacitor apparatus 60 of the fifth embodiment, a largernumber of capacitor electrodes may be formed. Of course, in suchcapacitor apparatus, one conductor opposed actuator in a manner bridgingover a large number of capacitor electrodes may be formed at theactuator, but plural conductors may be formed at the actuator toconstitute independent plural multiple operating capacitors. Suchcapacitor apparatus constitutes capacitor which can change a largenumber of electrostatic capacities by respective capacitor electrodesand conductor.

In the capacitor apparatus according to the present invention, specificcapacitor electrodes of a large number of capacitor electrodes arecaused to be common electrode and others are caused to be capacitorelectrode, whereby multiple operating variable capacitor is constituted.Accordingly, in the capacitor apparatus, various inductance elements arecombined with respective capacitor electrodes, thereby making itpossible to constitute, e.g., multiplex variable frequency filter,multiplex variable frequency oscillator or heterodynetransmitting/receiving circuit, etc.

INDUSTRIAL APPLICABILITY

As described above, the capacitor apparatus of the capacity variabletype according to the present invention is adapted to allow actuator inwhich there is formed as film conductor having dimensions to bridge overrespective capacitor electrodes to undergo, by drive means, an operationto come into contact with insulating substrate where at least twocapacitor electrodes are formed as film on one surface or to become awaytherefrom to thereby adjust opposite spacing between respectivecapacitor electrodes and conductor to constitute capacitor in whichelectrostatic capacity is variable. Accordingly, in accordance with thecapacitor apparatus of the capacity variable type, electric wiring withrespect to the conductor of the movable body side becomes unnecessary.From this fact, influence of parasitic inductance is reduced, andlowering of the entire resonance frequency is suppressed. Thus,capacitor in which the operation in the high frequency band can becarried out is constituted.

The capacitor apparatus of the capacity variable type according to thepresent invention is caused to be of the configuration in which fixedelectrode for drive is formed as film on the principal surface of theinsulating substrate along with respective capacitor electrodes in thestate where insulation with respect thereto is maintained, and movableelectrode for drive is formed as film along with the conductor at theactuator side in the state where insulation with respect thereto ismaintained to drive the actuator by electrostatic force generatedbetween the drive fixed electrode and the drive movable electrode.Accordingly, in accordance with the capacitor apparatus of the capacityvariable type, since the actuator is driven by drive voltage applied tothe drive fixed electrode and the drive movable electrode afterundergone positioning with high accuracy, capacitor in which low powerconsumption is realized and accuracy is high is constituted. Inaddition, in accordance with the capacitor apparatus of the capacityvariable type, since the electric signal system for capacitor and theelectric signal system for driving actuator are electrically insulated,mutual interference between the electric signal system and the drivesignal system utilizing variable capacitor formed at very small spacingis reduced. Thus, capacitor of high accuracy is constituted.

1. A capacitor apparatus of the capacity variable type comprising: aninsulation substrate in which at least two capacitor electrodes areformed on one surface in the state where insulation therebetween ismaintained with each other; an actuator formed by an insulatingmaterial, and having an external shape to bridge over the respectivecapacitor electrodes on one surface, the actuator being adapted so thata common conductor respectively constituting capacitors are formedbetween the conductor and the respective capacitor electrodes; and drivemeans for carrying out an operation to allow the actuator to be incontact with the principal surface of the insulating substrate, or toallow it to be away therefrom, wherein the actuator adjusts oppositespacing between the actuator and the insulating substrate by the drivemeans, whereby capacitance adjustment of the respective capacitors iscarried out; and wherein the drive means is composed of a fixedelectrode for drive formed on the principal surface of the insulatingsubstrate in the state where insulation with respect to the capacitorelectrode is maintained, and a movable electrode for drive formed at theactuator in correspondence with the drive electrode in the state whereinsulation with respect to the conductor is maintained, and wherein theactuator is driven by electrostatic force produced between the drivefixed electrode and he drive movable electrode by application of drivevoltage; wherein at least three capacitor electrodes or more are formedon the insulating substrate, and wherein either one of capacitorelectrodes is caused to be a common electrode to constitute capacitor bythis common electrode and other capacitor electrodes to therebyconstitute multiple operating capacitor which carries out interlockingoperation each other by the movable electrode and further wherein atleast one capacitor electrode has a draw-out portion.
 2. The capacitorapparatus of the capacity variable type as set forth in claim 1 whereinthe respective capacitor electrodes are formed so that their areas aredifferent from each other.
 3. A capacitor apparatus of the capacityvariable type comprising: an insulation substrate in which at least twocapacitor electrodes are formed on one surface in the state whereinsulation therebetween is maintained with each other; an actuatorformed by an insulating material, and having an external shape to bridgeover the respective capacitor electrodes on one surface, the actuatorbeing adapted so that a common conductor respectively constitutingcapacitors are formed between the conductor and the respective capacitorelectrodes; and drive means for carrying out an operation to allow theactuator to be in contact with the principal surface of the insulatingsubstrate or to allow it to be away therefrom, wherein the actuatoradjusts opposite spacing between the actuator and the insulatingsubstrate by the drive means, whereby capacitance adjustment of therespective capacitors is carried out; and wherein the drive means iscomposed of a fixed electrode for drive formed on the principal surfaceof the insulating substrate in the state where insulation with respectto the capacitor electrode is maintained, and a movable electrode fordrive formed at the actuator in correspondence with the drive electrodein the state where insulation with respect to the conductor ismaintained, and wherein the actuator is driven by electrostatic forceproduced between the drive fixed electrode and he drive movableelectrode by application of drive voltage; and wherein at least threecapacitor electrodes or more are formed on the insulating layer, and atleast two movable electrodes or more are formed at the actuator in thestate where insulation therebetween is maintained with each other, andwherein either two capacitor electrodes or more are caused to be commonelectrodes to constitute capacitor electrode by the common electrodesand other capacitor electrode or electrodes to thereby constitutemultiple operating capacitor which carries out interlocking operationeach other by the movable electrode and further wherein at least onecapacitor electrode has a draw-out portion.
 4. The capacitor apparatusof the capacity variable type as set forth in claim 3 wherein therespective capacitors are formed so that their areas are different fromeach other.